Light image display apparatus including selectively illuminated light piping elements

ABSTRACT

A light image display apparatus is described in which a plurality of light transmission elements are employed together with means for selectively applying light to the input ends of such elements in order to form a light image display by the illuminated output ends of such elements and to successively produce different images in the same display area by illuminating different combinations of elements. The light transmission elements may be flexible fibers of plastic or glass which are arranged in optically noncoherent bundles with the input ends of all elements in a bundle being irradiated simultaneously by the same light source and with the output ends of such elements being supported in different relative positions and spaced over a greater area than the input ends. The display apparatus may be used as a switch position readout for the switches on a cathoderay oscilloscope controlling its vertical amplifier gain and horizontal sweep rate by turning light bulbs on and off with such switches to selectively illuminate the light transmission elements and thereby produce light image displays of the switch positions. The switch position readout displays are positioned adjacent the faceplate of the cathode-ray tube employed in such oscilloscope, so that they may be viewed or photographed simultaneously with the electrical signal waveform produced on such tube to indicate the horizontal and vertical scale units of such waveform.

United States Patent [72] Inventors AndrewR. Burns;

' Peter J. Unger; Robert J. Rossman,

Beaverton,0reg.

[21] Appl.No. 770,483

[22] Filed Oct.25,1968

[45] Patented Apr. 6, 1971 [73] Assignee Tektronix,lnc.

Beaverton,0reg.

[54] LIGHT IMAGE DISPLAY APPARATUS INCLUDING SELECTIVELY ILLUMINATEDLIGHT PIPING ELEMENTS 15 Claims, 8 Drawing Figs.

[52] U.S.Cl 340/380,

{51] 1nt.Cl ..H04l23/00,

110413/00 [50] FieldofSearch 340/380, 324.1; 178/30 [56] ReferencesCited UNITED STATES PATENTS 2,554,580 5/1951 Goff 340/380 3,187,3216/1965 Kameny.. 340/345 3,387,084 6/1968 Hineetal.. 340/324.1

3,406,252 10/1968 Thomas 340/380X 3,420,949 1/1969 McNaney 340/380XPrimary ExaminerHarold I. Pitts Attorney-Buckhom, Blore, Klarquist andSparkman ABSTRACT: A light image display apparatus is described in iwhich a plurality of light transmission elements are employed togetherwith means for selectively applying light to the input ends of suchelements in order to form a light image display by the illuminatedoutput ends of such elements and to successively produce differentimages in the same display area by illuminating different combinationsof elements. The light transmission elements may be flexible fibers ofplastic or glass which are arranged in optically noncoherent bundleswith the input ends of all elements in a bundle being irradiatedsimultaneously by the same light source and with the output ends of suchelements being supported in different relative positions and spaced overa greater area than the input ends. The display apparatus may be used asa switch position readout for the switches on a cathode-ray oscilloscopecontrolling its vertical amplifier gain and horizontal sweep rate bytuming light bulbs on and off with such switches to selectivelyilluminate the light transmission elements and thereby produce lightimage displays of the switch positions. The switch position readoutdisplays are positioned adjacent the faceplate of the cathode-ray tubeemployed in such oscilloscope, so that they may be viewed orphotographed simultaneously with the electrical signal waveform producedon such tube to indicate the horizontal and vertical scale units of suchwaveform.

PATENTEUAPR elem 3,573,313

SHEET 1 OF 2 BUG/(HORN, ELORE, KLAROU/ST 8 SPAR/(MAN A7 TOHWEYSPATENTEUAPR 6197! 3,573,813

SHEET 2 OF 2 ANDREW R. BRUNS PETER J. U ER ROBERT L, ROS AN lA/VE/VTORS.

BUG/(HORN, BLUFF, KLA/VOU/ST 8 SPAR/ MAN 147' 7' ORA E Y5 LIGHT IMAGEDISPLAY APPARATUS INCLUDING SELECTIVELY ILLUMINATED LIGIIT PIPINGELEMENTS BACKGROUND OF THE INVENTION The subject matter of the presentinvention relates generally to light image display apparatus in whichthe display image is formed by the illuminated output ends of lighttransmission elements, and in particular to a display apparatus whichincludes control means for selectively illuminating such ele ments sothat a plurality of different light images are formed successively inthe same display area by different combinations of illuminated elements.

The display apparatus of the present invention differs from that ofconventional light image display apparatus which are either of the imagetransmission type in which coherent bundles of fiber optic elements areemployed to transmit light images from the input end to the output endthereof, or the display illumination type in which light pipes areemployed merely to transmit light from a source to a separate displaymember to illuminate such display member. In neither of theseconventional apparatus is the light image display fonned by theselectively illuminated output ends of the light pipes in the manner ofthe present invention.

The light image display apparatus of the present invention is especiallyuseful as a switch position readout device to indicate the position of amovable contact of the switch. Thus several of the present displayapparatus may be mounted in a position remote from the switch, such asadjacent the faceplate of a cathode-ray tube in a cathode-rayoscilloscope I and used to indicate the position of the switchescontrolling the horizontal sweep rate and vertical amplifier gain ofsuch oscilloscope. This enables the light image display of the switchposition readout to be viewed or photographed simultaneously with theelectrical signal waveform produced on the phosphor screen of thecathode-ray tube, such display indicating the units of the horizontaland vertical scales of such waveform to enable faster and easierinterpretation of the waveform characteristics. Thus the switch positionreadout display eliminates any possible error in reading the switchsettings on their dials or in interpreting a photograph of the waveformat a later time when the horizontal and vertical scale units do notappear in the photograph.

The light image display apparatus of the present invention has severaladvantages over the above-mentioned prior art apparatus. Thus thepresent apparatus provides an extremely compact display which occupiesvery little space on the front panel of the oscilloscope. In addition,it employs light transmission elements which need not be in the form ofcoherent fiber optic bundles, since such elements do not transmitimages, but merely form images by their illuminated output ends. As aresult of using noncoherent fiber optics the present display apparatusis less expensive to manufacture. A further advantage of the presentinvention is that it is of uncomplicated structure but is extremelyversatile since it is capable of producing a plurality of differentlight images successively in the same display area by selectivelyilluminating different combinations of light transmission elements atleast some of which form parts of several different images. The decoderdisplay apparatus described in U.S. Pat. No. 3,l09,065 of J. T. McNaneyis somewhat similar in operation to the present display apparatus but isof a much more complicated-and expensive construction. Thus such decoderemploys 64 input matrixes of light conducting elements which areinterconnected with the light conductive elements of a single outputmatrix so that each output element has 64 input elements connectedthereto. In spite of its large size and complicated construction thisdecoder is only capable of producing one character at a time.

It is therefore one object of the present invention to provide animproved light image display apparatus which is simple, inexpensive andis capable of producing a plurality of different light images.

Another object of the present invention is to provide an improved lightimage display apparatus which is compact and versatile, that employs aplurality of light transmission elements and means forselectivelyilluminating the output ends of such elements to' producedifferent light images successively in the same display area.

Still another object of the invention is to provide a light imagedisplay apparatus which forms light images without the use of coherentfiber optics.

A further object of the present invention is to provide a light imagedisplay apparatus which can be employed as a switch position readoutdevice.

An additional object of the present invention is to provide a lightimage display'apparatus which may be employed in a cathode-rayoscilloscope as a switch position readout adjacent the faceplate of acathode-ray tube to indicate the settings of its vertical gainswitch andhorizontal sweep rate switch so that the waveform produced on such tubeand the switch position readout display may both be simultaneouslyviewed or photog raphed, thereby reducing errors in interpretation ofthe waveform's characteristics.

BRIEF DESCRIPTION OF DRAWINGS parts broken away for clarity;

FIG. 3 is a vertical section view taken along the line 33 of FIG. 2;

FIG. 4 is a vertical section view taken along the line L4 of FIG. 2; I

FIG. 5 is a horizontal section view taken along the line 5-5 of FIG. 2;

FIG. 6 is an enlarged elevation view of the front of one of the displayapparatus of the present invention takeri along the line H of FIG. 2;

FIG. 7 is an elevation view of the front of another embodiment of thedisplay apparatus of the present invention; and I FIG. 8 is aperspective side view of the apparatus of FIG. 7 schematically showingpart of the light source control circuit associated therewith.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As shown in FIG. 1, acathode-ray oscilloscope 10 may be provided with three of the presentlight image display apparatus I2, 14 and I6, mounted on the front panelof theoscilloscope adjacent the faceplate 18 of a cathode-ray tube insuch oscilloscope. A conventional graticule scale 20 formed by aplurality of intersecting horizontal and vertical lines is provided onthe interior surface of the faceplate I8 oron a separate external memberover such faceplate. The divisions of the graticule scale 20 indicatethe horizontal and vertical dimensions of any electrical signal waveformproduced on the phosphor screen which is supported on the inner surfaceof the faceplate 18. At least two of the display apparatus 12, I4 and 16are employed as switch position readout devices,- respectively, for thevertical amplifier gain switch and the horizontal sweep rate switch ofthe oscilloscope. These display apparatus produce light image displaysof the positions of the above-mentioned switches which control thevertical and the horizontal circuits that cause deflection of theelectron beam within the cathode-ray tube to form the signal waveformin' a conventional manner. Thus the switch position readout displayproduced by the display apparatus 12 can indicate the units of thehorizontal axis of the graticule scale 20, for example, in seconds perdivision, while display apparatus 14 indicates the units of the verticalaxis of such graticule scale, for example, in volts per division. Thethird display apparatus I6 may be employed to convey other informationregarding the waveform display, or in the case of a dual traceoscilloscope it may indicate the position of a second vertical amplifiergain switch controlling the formation of a second waveform.

As shown in FIGS. 2 to 5, each of the display apparatus l2, l4 and 16include a display member 22 at its front end and a plurality of lighttransmission elements or light pipes" 24 of light transparent materialwhich extend through openings in the display member so that their outputends 26 terminate at the front surface of such member. The displaymember 24 is made of a light opaque material and the light transmissionelements are fixedly secured to such display member by a glue" layer 28of any suitable light opaque material such as epoxy resin, to preventlight coupling between such elements.

The light transmission elements 24 may be in the form of cylindricalfibers of flexible light transparent glass or plastic material which maybe coated with material having a high index of refraction. For example,the elements 24 may be made of a clear styrene plastic fiber having anacrylic plastic outer coating, and the display member 22 may be made ofa black resin plastic to increase contrast between the light imagedisplay and its background.

Each display apparatus includes a pair of support blocks 30 made oflight opaque material, such as aluminum, supported in alignment with thedisplay member 22 with one of such blocks positioned between the displaymember and the other block. Each of the support blocks is provided witha plurality of cavities 32 in its rear surface and within each cavity alight bulb 34 is mounted. A passageway 36 extends from the front surfaceof such block to an opening in the bottom of each cavity 32. The inputends 38 of the light transmission elements 24 are mounted within thepassageway 36 so that light emitted from light bulbs 34 is applied tosuch input ends. The light transmission elements 24 may be arranged inbundles of elements and the bundles inserted in passageways 36 so thatall of the input ends of the elements in each bundle are simultaneouslyilluminated by the same light bulb. In FIG. 6, all of the output ends 26of the light transmission elements in the same bundle have beenindicated by the same letter for purposes of clarity.

A pair of opaque plastic guide plates 40 having holes drilledtherethrough for different ones of the bundles of light transmissionelements 24 are employed to hold such elements after they are separatedinto the proper bundles. The guide plates are fastened to the front ofthe two support blocks 30 by screws or snap-on tabs projecting from suchguide plates into holes in the fronts of the support blocks. A pair oflight bulb mounting plates 42 of opaque plastic material are provided,each having openings therethrough in which the bases of the light bulbs34 are mounted. The mounting plates 42 are attached to the rear surfacesof both support blocks 30 by screws or snap tabs in a similar manner toguide plates 40. A pair of printed circuit boards 44 are attached to therear of the mounting plates 42 and are provided with a pair of holesadjacent each light bulb to enable the two leads of an incandescentfilament 46 of such bulb to be soldered thereto.

As shown in FIG. 2, a plurality of electrical leads 48 are connectedbetween the printed circuit board and the stationary contacts 50 on oneswitch wafer of a rotary switch 51 whose movable contract is rotated bya knob 52. The switch 51 may be the vertical amplifier gain switch orthe horizontal sweep rate switch of the oscilloscope, and has otherwafers (not shown) with stationary contacts corresponding to contacts 50that control one of the deflection circuits of such oscilloscope. Thusthe light bulbs 34 are turned on and off by rotation of the switch knobto selectively illuminate the output ends of the light piper 24 andproduce a display indicating the position of the movable contacts in theswitch.

As shown in FIG. 3, the rear support block 30 and its associated guideplate 40, printed circuit board 44 and mounted plate 42 are all providedwith U-shaped apertures 54 through which extend the lead wires 48attached to the printed circuit board 44 of the front support block,such lead wires being surrounded by a plastic insulating sleeve 56.Similarly FIG. 4 shows a larger rectangular aperture 58 provided throughthe front support block 30 and its associated guide plate, mountingplate, and printed circuit board to enable the bundles of lighttransmission elements for the rear support block to pass therethrough,such light elements being surrounded by a protective sleeve 60 ofplastic material.

The display member 22 and two support blocks 30 are attached to amounting plate 62 by bolts 64 and screws 66, respectively, as shown inFIG. 5. A light opaque cover 68 of aluminum is provided over the top andsides of these members to form therewith a light-tight housing for thelight transmission elements 24. The cover 68 is fastened to the frontsupport block 30 by screws 70, and tabs 72 projecting from the top ofboth mounting plates 42 which extend through holes in the housing foralignment purposes.

The switch position readout display on the front of the display member22 of the display apparatus 12 connected to the horizontal sweep rateswitch, is shown in FIG. 6. The display has six character display areaswhich are, beginning in the upper left-hand comer, l) (2) 1,2 or 5, (3)0, (4)0, (5) m or and (6) V or S. Thus the first character display 74 inthe shape of the symbol meaning greater than," is formed by the outputends 26 of five light transmission elements 24, which have the samereference letter C indicating they are all from the same bundle and allilluminated by the same light bulb. The second character display 76 iscapable of producing the light images of a l, a 2, or a 5, depending onwhich combination of the elements 24 in bundles H,J,K,L,M isilluminated, so that a plurality of different characters may be formedsuccessively on the same display area. A light image of the character 1is produced when the K and H light transmission elements areilluminated. A light image of the character I is produced when the L, Kand 1 elements are illuminated. A light image character 5 is producedwhen the K, L, M elements are illuminated. It should be noted that inthe second character display 76, the K and L elements are common to atleast two different characters and the K elements are common to allthree characters. Thus some light pipes form parts of several differentcharacters in the present display apparatus.

The third character display 78, and the fourth character display 80 areboth only of the character 0. However, a fifth character display 82 iscapable of producing light images of the characters m or p. whichrespectively stand for milli" and micro. Thus when the elements E areilluminated, the character [L is displayed. A sixth character displayarea 84 is provided for displaying the characters S or V, whichrespectively stand for Seconds and Volts. Thus when the elements K and Fare illuminated, the character S is displayed, while when the elements Gand K are illuminated the character V is displayed. In the sixthcharacter display 84 the elements K are common to two differentcharacters. Also it should be noted that the K elements are present bothin the second display 76 and the sixth display 84, even though the Kelements are all in the same bundle which is illuminated by a singlelight bulb.

Another embodiment of the display apparatus of the present invention isshown in FIGS. 7 and 8, which may be employed to produce a light imageof all 10 digits from 0 to 9 by selectively illuminating differentcombinations of seven light transmission elements 86, each having aninput end 88 and an output end 90. The light transmission elements 86forming the parts of the character display can each be in the form of abundle of light pipes or fibers, as in the embodiment of FIG. 5, or theymay be formed of a single light guide member. The output end 90 ismolded into an elongated substantially rectangular shape, which may belarger and of a different shape than its input end 88, which, in mostcases, would be circular. Thus the output ends 90 may be molded on oneend of cylindrical members of light transparent glass or plasticmaterial.

The light guides 86 may be selectively illuminated by turning on lightbulbs 92 positioned adjacent their input ends 88 by closing switches 94connecting the filaments of such light bulbs to a battery 96 or othersource of electrical current in a similar manner to the embodiment ofH05. 2 to 6. However, it is also possible to employ a single lightsource, together with a movable mask or shutter mechanism whichselectively transmits light from such source to the input ends 88 of thelight guide members. One such mask could be in the form of a rotary maskplate of light opaque material provided with radial rows of apertureswhich rotates with the switch shaft to selectively illuminate the outputends 90. Thus the input ends 88 of the elements 86 are each aligned withone aperture in each row, except in those switch positions in which theelement is not to be illuminated.

The operation of the display apparatus of HO. 7 is as follows to producelight images of all the ID numbers 0 to 9. To form a 1, light guides Pand R are illuminated. To form a 2, light guides W, P, X, T and Y areilluminated. To form a 3, light guides W, P, X, R and Y are illuminated.To form a 4, light guides S, X, P and R are illuminated. To form a 5,light guides W, S, X, R and Y are illuminated. To form a 6, light guidesW, S, T, Y, R, and X are illuminated. To form a 7, light guides W, P andR are illuminated. To form an 8, all of the guides are illuminated. Toform a 9, guides W, P, X, S and R are illuminated. To form an 0, guidesW, P, R, Y, T and S are illuminated, Thus 10 different characters areformed in the same display area by selectively illuminating differentcombinations of seven different light guides 86, the output ends ofwhich each form parts of several different characters.

It should be noted that while the light bulbs are shown operated bymechanical switches, they may also be operated by electronic switchessuch as transistors, to enable the display apparatus of FIGS. 7 and 8 tobe employed as the readout of an electrical pulse counter. To furtherincrease the speed of operation of the display other light sources whichhave a faster response time, such as light emitting diodes can beemployed in place of the incandescent lamps. In addition, while theswitch position display apparatus of the present invention has beenshown mounted in a position remote from the switch, because of itsminiature size, such display apparatus may be mounted directly on thecenter portion of the knob controlling such switch. This is especiallyuseful when the invention is employed to indicate the scale units of anelectronic counter, voltmeter, ammeter, portable television receiver orother small electronic instmment.

It will be obvious to those having ordinary skill in the art that manychanges may be made in the above-described preferred embodiments of thepresent invention without departing from the spirit of the invention.Therefore the scope of the present invention should only be determinedby the following claims.

We claim:

1. A light image display apparatus, comprising:

a plurality of light transmission elements having input ends and outputends, said elements being optically separated so that light is nottransmitted from one element to another element;

support means for supporting the light transmission elements so that theoutput ends of elements are positioned in display groups with the outputend of each element forming part of at least one image display and withat least some output ends each forming parts of a plurality of differentcharacters in the same one display area, and for supporting the inputends of said elements in different relative positions than their outputends; and

control means for selectively applying light to the input ends of saidelements in order to illuminate the output ends of the selected elementsand cause said illuminated output ends to produce a light image display,and for changing the light image display by illuminating different onesof said elements, said control means producing the light images of saiddifferent characters successively in said one display area byselectively illuminating different combinations of said output ends.

2. A display apparatus in accordance with claim I in which the lighttransmission elements are made of a flexible light transparent materialand have the same number of input ends and output ends.

3. A display apparatus in accordance with claim 1 in which the controlmeans couples the input ends of several light transmission elements in adisplay group to a single light source.

4. A display apparatus in accordance with claim 3 which also includes aswitch means for changing the connections in an electrical circuit, andsaid control means includes a plurality of light bulbs which areelectrically energized when the control means is operated by movement ofsaid switch means to produce a different illuminated character displayfor each switch position which indicates the position of said switch.

5. A display apparatus in accordance with claim 2 in which the lighttransmission elements are in the form of a plurality of separate bundlesof said elements with the output ends of the elements of each bundletogether forming a single part in several different characters and allof the input ends of the elements of a bundle being simultaneouslyirradiated with light from the same light source in one position of thecontrol means.

6. A display apparatus in accordance with claim 1 in which the lighttransmission elements are in the form of single individual light guideseach of which has an output end in the shape of a single part in severaldifferent characters, and the input ends of the light guides are eachirradiated with light by the control means in a separately controllablemanner.

7 A display apparatus in accordance with claim 5 in which said elementsare fibers of uniform cross section along their length so that the inputend and the output end of each element are both of the same size andshape.

8. A display apparatus in accordance with claim 6 in which the lightguides are of nonuniform cross section along their length and haveoutput ends which are larger and of a different shape than their inputends.

9. A display apparatus in accordance with claim 1 in which the supportmeans includes a display member of light opaque material having aplurality of separate holes extending therethrough from the back to thefront of said display member, and the light transmitting elements aremounted within said holes with their output ends terminating adjacentthe front surface of said display member so that the illuminated ones ofsaid output ends form the display.

it). A display apparatus in accordance with claim 9 in which the controlmeans includes a plurality of light bulbs mounted within cavitiesprovided in one side of a support block of light opaque material andswitch means connected to said light bulbs for selectively switchingthem on and off, and the input ends of the light transmitting elementsare'mounted within passageways extending from the opposite side of saidsupport block to openings in the bottom of said cavities so that saidinput ends are irradiated by light emitted from said bulbs.

11. A display apparatus in accordance with claim 10 in which theelectrical leads of the light bulbs are attached to a circuit boardsecured to said one side of said support block.

12. A display apparatus in accordance with claim 11 which includes atleast a pair of support blocks with associated light transmissionelements, light bulbs and circuit boards, one of said pair of supportblocks being positioned between the display member and the other supportblock, and said one support block being provided with an aperturethrough which extend the light transmitting elements of the othersupport block,

13. A display apparatus in accordance with claim 4 in which the outputends of the light transmission elements are supported adjacent the faceplate of a cathode-ray tube in a cathode-ray oscilloscope which iscontrolled by said switch means.

14. A display device in accordance with claim 13 in which the switchmeans changes the connections of a deflection circuit which controls thedeflection of the electron beam of said tube to vary the scale of theimage produced on the phosphor screen of such tube and the displaydevice produces a light image of a character display indicating saidscale.

nected to 21 similar display device which provides switch posi- Lionreadouts for such switches by forming two separate illu minzztcdcharacter displays.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No.3,573,813 Dated Agril 6 1971 nventor(s) ANDREW R. BRUNS, PETER J. UNGER& ROBERT L. ROSS! It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

"Andrew R. Burns" should be --Andrew R. B:

Cover page "Robert J. Rossman" should be -Robert L.

man;

Column 3, line 16 "24" should be -22-;

Column 3, line 23, "high" should be -low;

Column 3, line 51, "are" should be -may be--;

Column 3, line 67, "contract" should be --contact;

Column 3, line 74 "piper" should be pipes--;

Column 4, line 1, "Fig. 3" should be -Figs. 3 and 5;

Column 4, line 2, "mounted"should be -mounting;

Column 4, line 6, after "sleeve 56" should be --which,

however, may be omitted--;

Column 4, line 38, "A light image of the character 1" should be --Alight image of the character 2--;

Column 4 between lines 51 and 52 insert --character "m" is displayed,while when elements D are illuminated, the-- Column 5, line 60, after"output ends of" insert said-- Signed and sealed this 19th day ofOctober 1971.

(SEAL) Attest:

ROBERT GOT'ISCHALK EDWARD M.FLETCHER,J'R.

Acting Commissioner of P Attesting Officer

1. A light image display apparatus, comprising: a plurality of lighttransmission elements having input ends and output ends, said elementsbeing optically separated so that light is not transmitted from oneelement to another element; support means for supporting the lighttransmission elements so that the output ends of elements are positionedin display groups with the output end of each element forming part of atleast one image display and with at least some output ends each formingparts of a plurality of different characters in the same one displayarea, and for supporting the input ends of said elements in differentrelative positions than their output ends; and control means forselectively applying light to the input ends of said elements in orderto illuminate the output ends of the selected elements and cause saidilluminated output ends to produce a light image display, and forchanging the light image display by illuminating different ones of saidelements, said control means producing the light images of saiddifferent characters successively in said one display area byselectively illuminating different combinations of said output ends. 2.A display apparatus in accordance with claim 1 in which the lighttransmission elements are made of a flexible light transparent materialand have the same number of input ends and output ends.
 3. A displayapparatus in accordance with claim 1 in which the control means couplesthe input ends of several light transmission elements in a display groupto a single light source.
 4. A display apparatus in accordance withclaim 3 which also includes a switch means for changing the connectionsin an electrical circuit, and said control means includes a plurality oflight bulbs which are electrically energized when the control means isoperated by movement of said switch meaNs to produce a differentilluminated character display for each switch position which indicatesthe position of said switch.
 5. A display apparatus in accordance withclaim 2 in which the light transmission elements are in the form of aplurality of separate bundles of said elements with the output ends ofthe elements of each bundle together forming a single part in severaldifferent characters and all of the input ends of the elements of abundle being simultaneously irradiated with light from the same lightsource in one position of the control means.
 6. A display apparatus inaccordance with claim 1 in which the light transmission elements are inthe form of single individual light guides each of which has an outputend in the shape of a single part in several different characters, andthe input ends of the light guides are each irradiated with light by thecontrol means in a separately controllable manner.
 7. A displayapparatus in accordance with claim 5 in which said elements are fibersof uniform cross section along their length so that the input end andthe output end of each element are both of the same size and shape.
 8. Adisplay apparatus in accordance with claim 6 in which the light guidesare of nonuniform cross section along their length and have output endswhich are larger and of a different shape than their input ends.
 9. Adisplay apparatus in accordance with claim 1 in which the support meansincludes a display member of light opaque material having a plurality ofseparate holes extending therethrough from the back to the front of saiddisplay member, and the light transmitting elements are mounted withinsaid holes with their output ends terminating adjacent the front surfaceof said display member so that the illuminated ones of said output endsform the display.
 10. A display apparatus in accordance with claim 9 inwhich the control means includes a plurality of light bulbs mountedwithin cavities provided in one side of a support block of light opaquematerial and switch means connected to said light bulbs for selectivelyswitching them on and off, and the input ends of the light transmittingelements are mounted within passageways extending from the opposite sideof said support block to openings in the bottom of said cavities so thatsaid input ends are irradiated by light emitted from said bulbs.
 11. Adisplay apparatus in accordance with claim 10 in which the electricalleads of the light bulbs are attached to a circuit board secured to saidone side of said support block.
 12. A display apparatus in accordancewith claim 11 which includes at least a pair of support blocks withassociated light transmission elements, light bulbs and circuit boards,one of said pair of support blocks being positioned between the displaymember and the other support block, and said one support block beingprovided with an aperture through which extend the light transmittingelements of the other support block.
 13. A display apparatus inaccordance with claim 4 in which the output ends of the lighttransmission elements are supported adjacent the face plate of acathode-ray tube in a cathode-ray oscilloscope which is controlled bysaid switch means.
 14. A display device in accordance with claim 13 inwhich the switch means changes the connections of a deflection circuitwhich controls the deflection of the electron beam of said tube to varythe scale of the image produced on the phosphor screen of such tube andthe display device produces a light image of a character displayindicating said scale.
 15. A display apparatus in accordance with claim14 in which the switch means includes at least two switches connected tothe horizontal deflection circuit and the vertical deflection circuit ofsaid oscilloscope, and each switch is connected to a similar displaydevice which provides switch position readouts for such switches byforming two separate illuminated character displays.